RF stealth technology is one of the most significant ways to guarantee the radar's survivability. The RF stealth algorithm of MIMO radar in searching mode is obtained to improve the RF stealth performance. This algorithm is based on the RF stealth optimization model which sets the number of subarrays, average power, dwell time and search frame period as controllable parameters, the interception factor is also considered to optimize the RF stealth performance under the guarantee of searching performance. The simulation results show that MIMO radar with the RF stealth algorithm in searching mode has better stealth performance than conventional phased array radar.