To investigate the dynamic uncertainty of thrust of the pintle SDACM (solid divert and attitude control motor), the study focuses on the uncertainty of the thrust performance during variable operating conditions of the SDACM was carried out with the consideration of the uncertainties of the geometric parameters of the pintle gas valve. Computation model of the thrust during variable operating condition process of the SDACM was established by combining the working principle of the SDACM, the regular mathematical model of thrust and the zero-dimensional internal ballistic equation. On this basis, the uncertainty propagation was performed by Monte Carlo simulation method according to the uncertainty models of the geometry parameters of the SDACM, and the variation law of the thrust uncertainty over time after the transient motion of the pintle was obtained, thereby the uncertainty analysis of the thrust in the process of variable operating conditions was realized, and the uncertainty variables were weighted in order of importance. Quantification and evaluation of thrust uncertainty in the real-time regulation process of the SDACM can provide more reasonable design requirements for the control system, and save the development cost of the SDACM while meeting the design requirements.