This paper analyzes the performance of various indoor visible light co mmunication (VLC) systems with different channel matrix H of various parameters,such a s the distance between light emitting diodes (LEDs) d TX,the height between the transmitters plane and receivers plane h,and differ ent antenna layouts by changing the spatial distribution of LEDs and photo-detectors (PDs).Based on the simulatio n results,the key factors,which are critical to the performance of VLC systems,consist of the minimum Euclidean dist ance dmin and the determinant Det(H).According to these key factors,the a ntenna layouts are divided into two categories,namely the circular layout and lattice layout.As shown in the simulation results,if dTX is variable and 〖WT B X〗h is fixed,Det(H) is critical to the b it error rate (BER) of the system with a circular layout,while dmin and Det(H ) are critical to the BER of a system with a lattice layout.Moreover,dmin is the critical factor if dTX is within a certain range.If h is variable and d TX is fixed,Det (H) is the critical factor for the system performance.