Abstract: Pulsed power system on basis of photoconductive semiconductor switch (PCSS) is introduced. The output pulse is simulated according to shockley-read-hall model (SRHM), finite element method (FEM), and time-dependent voltage from the equivalent capacitance of Blumlein transmission line. PCSS made from semi-insulating GaAs (SI GaAs) is biased under high electric field 26.7 kV/cm and illuminated by laser at the wavelength of 1.064 micrometer for 1 nanosecond with 20 micro-joules. The agreement between the simulation result and the experimental result shows that in the condition of small capacitance of Blumlein transmission line (27.2 pF) PCSS can operate in linear mode in which the biased electrical field is at least up to 26.7 kV/cm.