Abstract：Objective To explore the effective reliability estimation analysis method before the design of engineering prototype.
Methods In this paper, the key subsystem equipment multi-leaf collimator (MLC) was taken as the research object. At the beginning,
the reliability prediction model was established according to MLC structural characteristics. The failure rate of electronic components
was calculated according to the GJB/Z299C-2006, the failure rate of mechanical components was calculated by finite element method,
experiment method, life analysis and other methods. In the last, the total failure rate was calculated according to the component
counting method and the logical relationship of design. Results The results showed that the theoretical mean time between failure
(MTBF) in the early stage of design was 376.5 h, which did not reach the theoretical expected index of 500 h. After identification
that was mainly due to the high failure rate of the lead screws and nuts, which became the weakest components of the whole
system. The expected service life was improved by improving the strength of the lead screw and optimizing the hardening process.
However, due to the technical limiting, it was difficult to reduce the failure rate of the drive wire mother, so it needed to be replaced
regularly to ensure the operation of the system, and it needed to be defined as the wearing part in the product maintenance strategy.
Conclusion In this paper, the potential risk can be exposed in the early stage of product development by the reliability estimation,
which can reduce the development cost and design cycle. The detailed and perfect analysis method for complex electromechanical
system summarized in this paper can be used as a reference for engineering technicians in reliability prediction work.