This paper reviews and contrasts the margining systems used by Taiwan Futures Exchange (TAIFEX) and the leading world futures and options exchanges. Our empirical analysis shows that the current margining system used by TAIFEX is neither risked-based nor portfolio-based and suggests that a new portfolio risk-based margining system be adopted at TAIFEX. While both SPAN and TIMS are portfolio-based and risk-based margining system, they are awkward to use for TAIFEX who trades index futures, index option and stock options. We modify SPAN and TIMS to propose a new margining system called Beta-Simulation to calculate margin requirements for TAIFEX. The new system uses the beta factor from single factor Market Model to simplify the appropriate collateral requirement offset estimate for inter-commodity spread. The new model is easier than SPAN in computational procedure but offers sounder theoretical basis than TIMS for credit offset estimates among individual stock options. Tested among all competing models, the new Beta-Simulation system proves to be the best margining system that can provide enough risk coverage with the most efficient margin requirements.