The mud pumps mainly have three models as SL3NB-1600A, SL3NB-1300A, SL3NB-1000, all of which are triplex single acting pistons. The characteristic of design is that to optimize parameter, appropriately increase stroke and reasonably lower stroke number improve the performance of suctions of pumps. The pump housing at power end is welded with the steel plate and is verified with finite element method. The crankshaft is a composed structure of straight axle and eccentric wheel. The crosshead extension rod adopts the elastic corrugated tube to seal. These two technologies got certificate of patent in China. The hardness of the driving gear is medium hard to improve its load carrying ability. The valve housing of hydraulic end with straight structure is massively forged thus the clearance volume is minimum. The K1:6 conical surface of the valve housing is treated with roll extrusion so the precision of fitting with the valve seat is greatly improved. The water inlet valve is positioned with strongback together with base plate which is convenient and reliable. The holes in the valve housing and the valve seat are machined according to API specifications. The serial products are produced by related international and domestic standards and are fully and strictly tested with the standards.