Rotodynamic multiphase pump can transport crude gas-liquid mixture produced from oil well, and is regarded as the good choice of oil-gas multiphase transportation in offshore product system, for its advantages that compact structure, large flow rate, not sensitive to solid particles in the fluid. However, it is prone to bring about gas-liquid separation within the impeller under high gas void fraction. To solve the problem, this paper presents several measures to break gas packet and inhibit gas-liquid separation, such as, depositing the short blades, opening holes at the blades where gas packets gather, using T-shaped blades, etc. Then, CFD software was used to simulate the flow fields which were added measures to inhibit gas-liquid separation. The results show that streamlines in three new impellers distribute more evenly than in original impeller, the gas-liquid two phases mixed degree was improved, and the gas-liquid separation was inhibited to some extent. However, adding the short blades and using T-blade impeller failed to improve the differential pressure of impellers. So the placement and the geometrical parameters of the measures inhibiting gas-liquid separation should be further optimized.