Contract

EXHIBIT 1: Joint Filing Agreement

In accordance with Rule 13d-1(k), promulgated under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree to the joint filing with all other Reporting Persons (as such term is defined in the Schedule 13D referred to below) on behalf of each of them of a statement on Schedule 13D (including amendments thereto) with respect to the common shares, par value $0.001 per share, of Sinovac Biotech Ltd., and that this Agreement may be included as an Exhibit to such joint filing. This Agreement may be executed in any number of counterparts, all of which taken together shall constitute one and the same instrument.

IN WITNESS WHEREOF, the undersigned hereby execute this Agreement as of May 31, 2011.

	SAIF Partners IV L.P.
	By:	/s/ Xxxxxx X. Xxx
		Name:	Xxxxxx X. Xxx
		Title:	Director of SAIF IV GP Capital Ltd., which is the General Partner of SAIF IV GP, L.P., which is the General Partner of SAIF Partners IV L.P.
	SAIF IV GP L.P.
	By:	/s/ Xxxxxx X. Xxx
		Name:	Xxxxxx X. Xxx
		Title:	Director of SAIF IV GP Capital Ltd., which is the General Partner of SAIF IV GP, L.P.
	SAIF IV GP Capital Ltd.
	By:	/s/ Xxxxxx X. Xxx
		Name:	Xxxxxx X. Xxx
		Title:	Director of SAIF IV GP Capital Ltd.