Abstract: Based on the basic concepts and characters of projections, coordinate systems and vectors, the set of fundamental equations formed by 4 constrained equations for orthogonal axonometric projection can be derived concisely. For 6 parameters of orthogonal axonometric projections, 2 parameters should be given firstly, and the other 4 parameters can be solved by the set of fundamental equations. For the all cases of giving 2 parameters, the solving equations of other parameters are derived correctly, and they are justified by numerical calculations.

Key words: engineering graphics, orthogonal axonometric projection, fundamental equation set, axonometric projection parameters