Influences of input optical pulses including the control pulse and probe pulse on the switching window of ultrafast nonlinear interferometer (UNI) are studied by numerical simulation and experiment. The power and width of input optical pulses are adjusted in the process of numerical simulation. In the beginning, the higher the powers of control pulse and probe pulse and the narrower the widths of them, the better the shape of the switching window. There are optimal values of the power of them for the best shape of the switching window. If the power of control pulse continues to increase, the top of the switching window inclines and the shape of the switching window gets worse. Similarly, if the power of probe pulse continues to increase, the extinction ratio of switching window would decrease. In the experiment of 10 Gb/s UNI, the continuous light is used to replace the probe pulse in order to observe the switching window. By changing the powers of control pulse and the continuous light, the results of simulation are verified. The experiment demonstrates that the high power and the narrow width of control pulse and the optimal power of continuous light should be selected. The result of experiment is quite similar to the simulation.