The temperature and humidity in the laboratory are major factors that affect the accuracy of the similar material simulation test. This paper introduced a new similar material simulation laboratory that can keep its temperature and humidity steady. Take the new laboratory as base, doing a test to simulate the rule of overburden rock’s separation precisely. The first step of test is measuring the simulated material’s hardening curve and regressively analyzing hardening curve function. Then doing errors correction to make the simulating result precise and deducing error-correcting formula. At last, getting the rule of a certain working face’s overburden separation using the new method of similar material simulation test.