With the advantages of high efficiency, high power, long lifetime, etc., laser diode is the best option for pumping of solid state lasers. As for the pumping, good optical performances which include beam divergence and pointing of laser diode are required. Because the divergence of laser diode bar at fast axis is very large, it is a hard work to collimate the beam and control the pointing of a bar, even harder to build a stack with good optical performance. Method of controlling beam quality of laser diode bar is studied, and a laser diode stack with 60 fast axis collimated bars is build up, the peak power of the stack is 18 kW, the total divergence (on fast axis) of the stack is less then 0.2° (3.5 mard), the pointing of each bar is within ±0.15° (±2.6 mrad).