The mass transfer reaction kinetics of NO absorption by UV/chlorine advanced oxidation process were investigated in a lab-scale photochemical bubble reactor. Effects of several parameters on NO absorption rate were studied, including UV power, NO inlet concentration, SO2 concentration, active chlorine concentration of electrolyzed seawater, and reaction temperature. Results showed that NO absorption rate increased gradually with the increase of UV power, NO inlet concentration, and active chlorine concentration of electrolyzed seawater, but was almost independent of SO2 concentration and reaction temperature (below 313 K). The absorption process is a pseudo-0.2-order with respect to NO, as well as a pseudo-0.6-order with respect to active chlorine. The mass transfer process is the main rate-determining step for the NO absorption by UV/electrolyzed seawater process. The established NO absorption model is in good agreement with the experimental values.