Aiming at the problem of security risk assessment of the installation project of position construction, according to the evidence reasoning algorithm, a security risk assessment method for the installation project of position construction is proposed. This paper decomposes the security risk factors into indicator layer step by step, and sorts out the correlations between the indicators, then constructs the security risk assessment index system of the installation project of position construction. According to the risk assessment result, RIMER (belief rule base inference methodology using evidential reasoning) is used to solve these problems that the underlying input indicators are diverse and the evaluation information is incomplete. The example analysis results show that the method has good explanatory and traceability, and it also has certain reference significance for the safety work in civil engineering and position management.