Please make your marriage license authenticated by Foreign Affairs Ministry of Sri Lanka and Chinese Embassy in Sri Lanka. Then your marriage license can be used in China.

You can apply for L visa for family visiting, your wife is Chinese, which is helpful for your L visa application, please prepare the below documents:
1.A valid passport as well as a copy of its information page: Your valid passport must have at least six (6) months of remaining validity and at least one blank visa page in it.
2.Application form: One completed Visa Application Form.
3.Photo: one recent photo of 2x2 square inch (black & white or color is acceptable) glued or stapled on the application form.
4. Marriage Licese and its copy
5. Under some situations, the round-trip flight tickets and financial certificate are also required.