A compound or hybrid turbo pump constructed by both of turbo blade and drag pumping elements is usually designed to get the best attributes of both types of pump at the same time. However, the complexities in rotor geometry incur problems for specific applications. A rotor configuration design for the new turbo booster pump which is combined a TMP section with a spiral groove rotor by a specially designed connecting blade and is successfully predicted by both of CFD and DSMC simulation methodologies has been conducted. The predicted and testing results show that this pump is effective to operate in an inlet pressure range from 10-7Torr to around 10Torr with a maximum pumping speed appropriately 1000L/s in free molecular regime. Modern semiconductor processes require a large gas throughput and an ultrahigh vacuum (UHV) pump to create an ultraclean process environment. And to choice a proper foreline pump with effective foreline capabilities to reduce contamination to process chambers is an important consideration issue for pump designs and applications. Therefore, it is imperative to investigate the foreline performance of this pump to optimize its function. In this article, a testing system designed to measure the pumping speeds and the foreline capabilities of this pump is constructed. A conductance valve is attached between the turbo booster pump and the foreline pumps to study the optimum foreline speed for this new pump. By controlling valve conductance between HV pump and foreline pump, and by measuring the variations of pressures and throughput at inlet and outlet, the influences of foreline's speed upon the total performance of turbo booster pump are explored. Besides, to reduce cost of the mechanical booster pump and inherently danger of contamination from it, the substitution possibility using this new pump is also discussed.