Induced eddy currents in can cause loss when the canned motor runs, the loss make the motor`s temperature rise, directly affect the canned motor pump and the entire transmission system security. Empirical formula estimates eddy current losses which has a big error, it is difficult to meet the engineering requirements. For the canned motor with Hastelloy-C alloy or Sus316L cans, analyzed electromagnetic field and calculated can loss using a finite element method of Ansoft. The paper developed four prototypes, and obtained the experimental value of can loss via simple no-load experiment by the loss separation method. The results are compared with simulation value show that the accuracy of FEM is higher accurately than empirical formula; Analysis shows that dimension of a model and can material characteristic parameters such as the resistivity influence on the calculated error of FEM, the paper proposes to correct the error in the case of considering can material characteristic parameters.