A CO2 laser of 800 W and TEM00 mode has been successfully used for welding of the diamond tools. Through numerous experiments, a study of the effect of technological parameters, such as laser power, welding rate, vertical focal point and offset, upon welding quality of diamond tools is made and the optimal technological parameters of laser welding are obtained. The depth/width ratio being about 2 mm, and the maxium penetration depth about 1.2 mm are reached. The bond strength and the loading capacity of the diamond tools are greatly increased by the laser welding.