Laser　diode　pumped　microchip　lasers　passively　Q-switched　by　Cr4+:YAG,　with　high　repetition　rate,　short　pulse　width　and　high　peak　power,　have　important　applications　in　optical　communication,　lidar,　remote　sensing,　nonlinear　frequency　conversion,　laser　micro　-processing　and　so　on.　However,　in　these　lasers,　the　output　stability　is　poor　and　the　repetition　rate　of　output　laser　cannot　be　changed　widely.　This　will　restrict　the　applications　of　these　lasers　in　fluorescence　analysis　of　aerosols　or　ranging,　space　optical　communication.　In　the　experiment,　output　pulses　with　continuously　tunable　repetition　rate　from　2　kHz　to　28　kHz　and　stable　oscillation　were　obtained　in　the　laser　diode　pumped　microchip　laser　passively　Q-switched　by　Cr4+:YAG.　In　the　stability　of　single　pulse　energy　from　2　kHz　to　28　kHz　was　less　than　±　2.50%.　Stable　2.431　ns　pulse　at　20　kHz　with　single　pulse　energy　of　17.6　μJ　and　extinction　ratio　of　252:1　and　with　amplitude　instability　of　4.00%　and　frequency　instability　of　2.40%　was　obtained.　This　laser　diode　pumped　microchip　laser　passively　Q-switched　by　Cr4+:YAG　with　wide　continuously　tunable　repetition　rate　and　stable　oscillation　will　have　broad　application　prospects.