We studied the anti-cold shock performance of activated sludge microbes (ASM) with magnetic field (MF) strengthening under slow and rapid cooling and rewarming. From stage S3 to S4, the TTC-DHA (triphenyltetrazolium chloride dehydrogenase) of reactor A₂ and B₂ were 98.5% and 72.5% higher than that of reactor A₁ and B₁, which showed that MF had a better strengthening effect on TTC-DHA under slow temperature variation than that under rapid temperature variation. MF had a definite strengthening effect on relief and inhibition of cell membrane lipid peroxidation and low-temperature injury, which was indicated by SOD (superoxide dismutase), CAT (catalase), and MDA (malonaldehyde), while the MF strengthening effect on SOD and CAT activity was not stable under rapid cooling and rewarming. The MF had little effect on phospholipid fatty acid (PLFA) diversity of ASM under slow cooling, but had higher PLFA diversity on that under rapid cooling. Optimal MF strengthening application under different temperature variation mode is supposed to be a potential pathway to strengthen the activity and cold resistance of ASM and improve the efficiency of wastewater treatment in low temperatures.