To study electromagnetic pulse (EMP) in the target chamber of nanosecond laser inertial confinement facility, this study uses the independently developed EMPIC-2D calculation software to perform the numerical simulation. The escaping electrons generated by the interaction of high-intensity laser pulses with solid target were considered as the input parameter and the electromagnetic pulse intensity in the chamber were considered as the as output. Results show that EMP frequency mostly distributes between 0 MHz and 2 GHz. As the width of the ejection waveform widens, the high-frequency nanosecond signal component decreases, while the low-frequency component slightly changes. Peak values of electromagnetic field (close to the electron emission point) also decrease with the extension of ejection time (1--10 ns). Compared with the simulation results of picosecond laser pulses, nanosecond simulation results have lower electromagnetic intensity. Its low frequency compositions are similar to picosecond results; however, high frequency compositions higher than 1 GHz are observed to greatly decrease.