The complete classification of 4-dimensional optimal self-orthogonal codes of code length is presented. The establishment of the optimal orthogonal code matrix and the formation of linear equations between the two links will determine the problem of optimal orthogonal code transforming into that of solving linear equations. Results identify all generator matrixes of the optimal orthogonal code, and further are not equivalent to the optimal orthogonal codes since the integrity of classification, and the generator matrices and weight polynomials of these 4-dimensional optimal self-orthogonal codes are also given. Therefore, the optimal orthogonal code parameters, structural characteristics and equivalence problem have been completely solved.