A quantitative methodology on constant pressure valve (CPV) stability analysis was presented. Firstly

the main parameters affecting static property of CPV were got by static analysis. The root-locus plots of CPV were achieved through small deviation dynamic analysis. By defining the concept of critical inlet pressure

the quantitative results of five main structural parameters' effect on the CPV stability margin was got: the spring stiffness has a little effect on stability margin; the increase of spool diameter

damping coefficient

load

and decrease of constant pressure chamber volume could enlarge the stability margin. The analytical result has an excellent consistence with AMESim simulation result and engineering experience. Finally

two conclusions were presented for enhancing the stability margin of CPV: (1) for improving problem of CPV

the most effective method is to change the outlet area; (2) for CPV design problem

based on the inlet pressure requirement and the minimum load

the critical inlet pressure need be determined firstly

and then the spool area and constant pressure chamber volume are taken as main design parameters by dynamic analysis.