The piecewise linear current density recursive convolution in finite-difference time-domain method is used to study the characteristics of one-dimensional unmagnetized plasma photonic crystals with a defect layer. In the frequency domain, the transmission ratios of electromagnetic Gaussian pulses are computed and we analyzed the effect on defect mode properties of unmagnetized photonic crystals produced by its periodic constant, parameters of plasma and parameters of the defect layer, such as its dielectric coefficient, length and position. The results show that different defect modes can be realized by changing the parameters.