NT 20-F
Washington, D.C. 20549
FORM 12b-25
                                                               Commission File Number 001-33107
(Check one):   o  Form 10-K þ  Form 20-F o  Form 11-K o  Form 10-Q o  Form 10-D o  Form N-SAR o  Form N-CSR
  For Period Ended:   December 31, 2009
    o   Transition Report on Form 10-K  
    o   Transition Report on Form 20-F  
    o   Transition Report on Form 11-K  
    o   Transition Report on Form 10-Q  
    o   Transition Report on Form N-SAR  
  For the Transition Period Ended:    

Read Instruction (on back page) Before Preparing Form.
Please Print or Type.
Nothing in this form shall be construed to imply that the Commission has verified any information contained herein.
If the notification relates to a portion of the filing checked above, identify the Item(s) to which the notification relates:
Canadian Solar Inc.
Full Name of Registrant
Former Name if Applicable

No. 199 Lushan Road
Address of Principal Executive Office (Street and Number)
Suzhou New District, Suzhou, Jiangsu 215129, People’s Republic of China
City, State and Zip Code



RULE 12b-25(b) AND (c)
If the subject report could not be filed without unreasonable effort or expense and the registrant seeks relief pursuant to Rule 12b-25(b), the following should be completed. (Check box if appropriate).
    (a)   The reason described in reasonable detail in Part III of this form could not be eliminated without unreasonable effort or expense;
    (b)   The subject annual report, semi-annual report, transition report on Form 10-K, Form 20-F, 11-K, Form N-SAR or Form N-CSR, or portion thereof, will be filed on or before the fifteenth calendar day following the prescribed due date; or the subject quarterly report or transition report on Form 10-Q or subject distribution report on Form 10-D, or portion thereof, will be filed on or before the fifth calendar day following the prescribed due date; and
      (c)   The accountant’s statement or other exhibit required by Rule 12b-25(c) has been attached if applicable.
State below in reasonable detail the reasons why Form 10-K, 11-K, 20-F, 10-Q, N-SAR, N-CSR, or the transition report or portion thereof, could not be filed within the prescribed time period. (Attach extra Sheets if Needed).
Canadian Solar Inc. (the “Company”) could not file its annual report on Form 20-F for the year ended December 31, 2009 within the prescribed time period because the Company has not yet completed the preparation of its financial statements.
(1)   Name and telephone number of person to contact in regard to this notification
Shawn (Xiaohua) Qu    86 (512)    66908088 
  (Area Code)   (Telephone Number)
(2)   Have all other periodic reports required under Section 13 or 15(d) of the Securities Exchange Act of 1934 or Section 30 of the Investment Company Act of 1940 during the preceding 12 months or for such shorter period that the registrant was required to file such report(s) been filed? If the answer is no, identify report(s).
    Yes þ     No o
(3)   Is it anticipated that any significant change in results of operations from the corresponding period for the last fiscal year will be reflected by the earnings statements to be included in the subject report or portion thereof?
    Yes þ     No o
    If so, attach an explanation of the anticipated change, both narratively and quantitatively, and, if appropriate, state the reasons why a reasonable estimate of the results cannot be made.



Because the Company has not finalized its financial statements for the year ended December 31, 2009, it is not possible at this time to provide a reasonable estimate of the change in results of operations from the year ended December 31, 2008.
Canadian Solar Inc. 
(Name of Registrant as Specified in Charter)
has caused this notification to be signed on its behalf by the undersigned thereunto duly authorized.
  June 30, 2010   By:   /s/ Shawn (Xiaohua) Qu
          Shawn (Xiaohua) Qu
          Chairman, President and Chief Executive officer