In the Optical Burst Switching Network, the burst assembly technique is one of the challenging issues in the implementation of the system. It has the influence on the burst characteristic, which gives an impact on the network performance. This paper report the OBS system performance observed in simulated 14-node network based on Just-Enough-Time (JET) reservation protocol and four burst assembly techniques. The point-to-point traffic flows in the network are generated by random Exponential ON-OFF sources. Simulation results indicate that the Threshold-based assembly scheme provides the lowest loss probability but with the highest average assembly delay. The Timer-counter-based method gives the highest loss probability variation. ne Fixed-based technique, which includes both burst size decision threshold and maximum delay time, to control the burst creation process, provides higher loss probability than the Threshold-based method but shorter average assembly delay. The Hysteresis-based method, which improves the Fixed-based method by using adaptable burst size decision value, can further reduce the loss probability and average assembly delay.