Microalgae fix inorganic carbon (CO2) into biomass that can be used as biofuels through photosynthesis. In microalgae-based photobioreactors, the poor distribution of light and CO2 source often limit the production. A promising solution for these problems is applying light waveguides to deliver the light uniformly and introducing hollow fibre membranes (HFMs) which can increase the interfacial contact area for gas transfer. There are several parameters that have impact on the efficiency of HFM reactor, such as light, temperature, gas velocity in fibre, inlet concentration of CO2, and distance between HFM arrays. Our research goal is using simulation methods to test those parameters, make predictions and help to simplify further experiments. The numerical model we used to approach the microorganisms in photobioreactors system, Monod equation model, has several empirical coefficients which need to be determined by experiments. Our group members have done the experiment testing how the fibre distance influences the algae growth. We redid the experiment on computer using COMSOL Multiphysics 4.3b, and the result matched well, which verified the reliability of the simulation model. Then we tested the effect of inlet concentration of CO2 and the gas velocity.