In order to evaluate ISO/CD19973-4, some items had been tested, such as step response, valve opening, feasible opening frequency, air consumption, piping influence, cycle response and so on. The results show that Valve opening varies sensitively to the size of piping, solenoid valve and test chamber. The valve of regulator opens to some extent, closes immediately, and never reaches the full opening. If these circuit specifications are defined concretely and observed strictly, it is not impossible to obtain a certain required opening ratio and air consumption is very large. On the side, the compared tests based on the Japanese JIS test circuit having been carried out, the results show that, regardless of test circuit specifications, the valve of regulator always repeats full closing and full opening. The relief valve of the regulator operates too. At the same operating frequency, air consumption is one digit less than the one in ISO/CD 19973-4 circuit. In the end, improved JIS circuit was put forward as a reliability circuit of pneumatic pressure regulator.