Abstract:The approximate calculation of integral values on the basis of the randomized trials and random events of probability is an important idea for integral approximate calculation. The said calculation method, compared with the approximation method, is simple and easy to handle in calculating numerical integration and with reliable accuracy. The use of projected point algorithm presupposes a function maximum value as a prerequisite, so first the computer calculation of the function maximum value is presented, then on the basis of the projected point algorithm the approximation integration calculation is put under discussion on the interval and the interval by turn, and at last the above two methods for integral calculation are popularized to cases of multi dimensional integration and for each case a computer simulation is provided.