In this thesis, carrier dynamics and broadband THz enhancement of photoconduction based THz system are studied with double pulses pump-probe and THz system. The carrier dynamics behavior of the second pulse excitation almost remain unchanged for various temporal spacing of double pulses excitation (from 264fs to 276fs). This is attributed to faster carrier life time of material (around 270fs). Meanwhile, broadband THz enhancement is also investigated under various chirp and temporal spacing of two excitation pulses using shaping pulse THz-TDS system. Compared to typical narrowband THz enhancement, enhanced broadband THz signal both in temporal profile and power is observed at specific temporal spacing and chirp of two excitation pulses. Suitable mechanics is also discussed in this thesis.