In[1] the method of truth table to solve Boolean equations was presented.But by that method the calculation quantity is huge. This article proved thatany Boolean equation of one unknown may be transformed into that of at mosttwo knowns by means of the change of known variables and obtained its generalsolution. The necessary and sufficient condition for existence of solution is alsoobtained. In the case of multi-unknowns and some equations of enumerableinfinite number of unknowns this method is also effective.