After a comprehensive consideration on the factors of coil, circuit, and power, this article gives, for the first time, a general theory of designing a standard capacitor discharge pulse magnet (winding coil, Bitter coil, or single turn coil).According to the theory, the optimum contruction parameters of the magnet and the parameters of the power (i0, F(α, β), a2, b, L, C, N, l, S, (or d), B, and Imax) can be caculated if only the figures of B0, 2a, 1/2 T, λ,σ, and v are given.This article also makes a physical study on the optimum construction of magnet.