The invention discloses an automatic testing method for the pH value of the methylamine nitrate manufacturing procedure. A pH value online testing device is arranged on a neutralization tank and provided with an automatic washing device, when a reaction is close to the terminal point, the pH value online testing device is started, and automatic testing of the pH value is completed through the pH value online testing device; washing of an online pH meter in the pH value online testing device is completed through the automatic washing device after the reaction is over, residual methylamine nitrate is washed down simultaneously, and the safety is guaranteed. According to the automatic testing method for the pH value of the methylamine nitrate manufacturing procedure, manual operation can be simulated, when the reaction is close to the terminal point, the pH value automatic testing device is started, and damage of the strong acid environment is effectively avoided; meanwhile, a through hole is formed in the end, far away from a clamping device, of a protecting bush, and the problem that due to the fact that a probe of the online pH meter is exposed in the air, the measuring veracity and the service life are affected are effectively solved; the automatic washing device conducts automatic washing after the reaction is over, the residual methylamine nitrate is washed down simultaneously, and the safety is guaranteed.