The cylinder test is one of the most commonly used tests to calibrate the parameters of the equation of state for explosive detonation products. A probe cylinder test platform was designed and established in order to determine the parameters of the JWL equation of state for explosive detonation products. A 20 ns high-resolution pulse chronograph and a set of probes with radial displacement differences were used to record multiple discrete points during the expansion process of the cylinder. When the cylinder expands to the head of the probe to form a circuit loop， the pulse chronometer records the time. Based on this， the displacement-time history curve of the cylinder wall can be obtained. Two probe cylinder tests of TNT explosives were carried out， and discrete points of cylinder expansion displacement were obtained. The experimental results show that the difference between the two sets of test curves is small， indicating that the probe cylinder test has good repeatability. The JWL equation of state parameters of TNT explosive detonation products were determined using the BP-GA algorithm. The determined JWL parameters were then substituted into the finite element software for numerical verification， and the results showed that the determination coefficient R² of the simulation displacement curve was 0.9997， indicating the high accuracy of JWL parameters.