Abstract: To measure the sweep nonlinearity of streak camera working at microsecond level, the system based on delay tunable signal source is developed and analyzed. The system is mainly constituted of a delay tunable signal source and a triggered short pulse laser. The short pulse laser is triggered by the delay tunable signal source. The streak camera records the laser pulses appearing at different channel of the streak camera as the signal sources delay value varies. The relation between the laser pulse peak channel and signal source delay value is fitted by the polynomial method. The polynomial is a denotation of the correlation between time and each channel. Sweep velocity and sweep nonlinearity are calculated with the polynomial. The fluctuation of the sweep nonlinearity measurement system is 0.7 ns. The fluctuation of the system causes the fluctuation of the measured sweep velocity through curve fitting process. The process is simulated by adding a Gaussian noise to the delay-channel raw data points. The mass simulation shows that the fluctuation of the delay-channel correlation is less than 2 ns. The sweep nonlinearity measurement system can also be used for calibrating streak camera working at several hundred nanosecond level.