Based on simple physical model and matrix optical method, the focusing adjustment formulas of plane wave, spherical wave and Gaussian beam from laser optical transmitting system are deduced. And the focusing adjustment properties of the three kinds of waves are calculated and analyzed. During plane wave focusing adjustment, with the decreasing of focusing adjustment quantity absolute value, focusing distance increases. When focusing adjustment quantity closes to zero, the increasing speed of focusing distance is faster. During spherical wave focusing, collimation emission status with infinity focusing distance exists. The emission wave beam becomes divergent if focusing adjustment quantity is over the values corresponding to the state. At the same time, with the increasing of the distance between spherical wave curvature center and secondary mirror, the focusing adjustment quantity corresponding to collimating emission state move right and close to zero. During Gaussian beam focusing and with same focusing adjustment quantity, there is an obvious difference between Gaussian beam waist and plane wave focus position in far distance. The difference can be reduced through increasing the waist width of incoming Gaussian beam and the expanded beam ratio of laser optical transmitting system and choosing shorter wavelength optical beam.