The crankshaft space force system of crank and connecting rod mechanism of gear transmission reciprocating pump was established for mechanical analysis on crankshaft crank pin shaft. Through adding balance strip to have rotating inertia force equilibrium and testing to change the interface position of intake pipe, the size change of intake and drainage channels at hydraulic end was found out to be caused by the water attack from the liquid in BW200 pump chamber, and the pump temperature increasing and crankshaft crank pin wearing were solved.