It is novel to apply magnetic field in the indoor air purification by collecting pre-charged suspended particles. Based on experiments and analysis of relative data, the effects of some influential factors (the number of discharge electrode, the polarity and magnitude of discharge voltage, the direction and magnitude of magnetic field, the initial velocity of charged particles, the distance between particle collecting plates) on the efficiency of air purification are discussed. The results indicate that the purification efficiency is improved by applying the proper magnetic field, -6 kV direct current voltage is an optimal voltage and there are optimal magnitudes of the distance between collecting plate and the initial velocity of particles in the purification process.