The structures of ultrathin sputtered Cr/C multilayers were determined by high-resolution transmission electron microscopy. The evolution of layer thickness errors, interdiffusion and interfacial roughness were simulated using time series models. The results show that with increasing of interdiffusion and roughness the multilayer thickness ratio changes, thereby influencing the optical performance. All structural parameters show good correlation with and influence adjacent layers. The system errors of the deposition equipment can also be evaluated by the models.