Photoconductive Antenna (PCA) is considered to be simple and compact source for the terahertz (THz) generation. PCA is a common device to generate THz signals. It uses optical-to-electrical conversion to generate the THz radiation. However, the major problem with PCA is the lower efficiency, which is below 1%. The efficiency of PCA systems depends on the current pulse generated by the photo-carriers through the ultrashort laser pulse excitation. In PCA, high efficiency can be achieved by generating a high amplitude current pulse. In this communication a 2D simulation study of current pulse formation is analyzed in the PCA. Also, the effect of different parameters such as input laser power, applied DC bias voltage, antenna and semiconductor material on current pulse generation has been studied to understand the behavior of PCA. The aim of this communication is to analyze the effect of different parameters at low laser power where the screening effect can be neglected. This work is expected to provide better understanding of the mechanism of THz generation and in deciding optimum parameters for maximizing Optical-to-THz conversion efficiency of PCA. © 2015 IEEE.