Abstract: At present there are still few programs for calculating either discrete quantities or discrete quantities and continuous quantities optimal design. However, if there are discrete quantities in the design variables, such as the numbers of gear teeth, gear modulus and the thichness of the steel plate, one needs a program for integer variables. This article describes a method based on the grid method which calculates iterative-ly according to the variations of design variables using continuous quantities or discrete quantities respectively to find the ideal optimal solution. Based on this method, a program has been developed for integer variables in optimal design using ALGOL, and some examples are also attached. This program is easy to understand and quite flexible. It could be helpful in calculating the solutions to small scale questions with discrete and continuous variables.