Based on One-coincidence Sequence (OCS), a new two-dimensional optical orthogonal code named EQC/OCS is constructed. EQC/OCS uses Extended Quadratic Congruencies (EQC) for time spreading and OCS for wavelength hopping. Compared with EQC/PC, the number of wavelengths for EQC/OCS is not limited to a prime number. EQC/OCS can be constructed flexibly, and also can use available wavelengths effectively. When the number of available wavelengths is not a prime number, EQC/OCS has larger code cardinality of two-dimensional Optical Code Division Multiple Access (OCDMA) than that of EQC/PC under the same code length and code weight. On the other hand, compared with EQC/PC, EQC/OCS has the same performance of autocorrelation and cross-correlation.