We proposed an improved Fizeau's experiment to test covariant rules of electromagnetic and optic phenomena in media[1]. This paper is to provide convenience to whom are interested to carry out the experiment. The drag coefficient is [see PDF for equation] when the light path is in rest liquid whose refractive index is n' in the tank. If the tank is empty, n'=1 and the formula will be reduced to the known [see PDF for equation] of the conventional Fizeau's experiment. Especially, the coefficient is [see PDF for equation] provided . The cost is very low and we hope it will be performed as soon as possible.