Time-dependent　system　kinematic　reliability　of　the　planar　parallel　manipulator　refers　to　the　probability　of　the　pose　error　falling　into　the　allowable　safe　region　over　the　whole　specified　trajectory,　which　is　essential　for　its　work　performance.　However,　works　regarding　this　issue　are　quite　limited.　Consequently,　this　study　conducts　time-dependent　kinematic　reliability　analysis　for　planar　parallel　manipulators　considering　joint　clearance,　input　uncertainty,　and　manufacturing　imperfection　based　on　the　first-passage　method.　First,　the　limit-state　pose　error　function　is　established　by　means　of　the　Baker–Campbell–Hausdorff　formula　and　the　theory　of　the　Lie　group　and　Lie　algebra.　Then,　the　analytical　solution　to　the　outcrossing　rate　of　the　non-stationary　vector　stochastic　kinematic　process　is　derived　by　employing　the　expectation　propagation　and　closed-form　properties　of　conditional　and　marginal　statistical　moments　(mean　and　covariance)　of　the　multivariate　Gaussian.　On　this　basis,　the　time-dependent　system　kinematic　reliability　is　calculated　upon　the　assumption　that　the　outcrossing　events　are　independent.　Finally,　the　planar　3-RRR　parallel　manipulator　is　used　to　demonstrate　the　proposed　method,　and　its　effectiveness　is　validated　by　comparison　with　the　Monte　Carlo　simulation　method.　©　2020　Elsevier　Ltd