I am now working in a project site of Shanghai Yingdun Security Company. I have been working 12 hours every day for two months without a day off. ...

Ask the local labor department for help, bring the necessary things, your attendance record, and see if the contract you signed with the company has no restrictions on resignation. There are generally restrictions. If there is, at the same time, the company will not ask you to resign, and you will leave yourself. If the company wants to investigate your responsibility, it should also bear legal responsibility. Therefore, it is best to see what kind of cooperation the local labor department needs.