We have studied kinetics of random sequential adsorption of mixtures on a square lattice using Monte Carlo method. Mixtures of linear short segments and long segments were deposited with the probability p and 1-p, respectively. For fixed lengths of each segment in the mixture, the jamming limits decrease when p increases. The jamming limits of mixtures always are greater than those of the pure short- or long-segment deposition. For fixed p and fixed length of the short segments, the jamming limits have a maximum when the length of the long segment increases. We conjectured a kinetic equation for the jamming coverage based on the data fitting.