The pyroelectricity of Pb0.99Nb0.02［(Zr1-xSnx)1-yTiy］0.98O3 antiferroelectric and ferroelectric ceramics is investigated. Experimental results show that phase transitions are accompanied with drastic electric current changes and form positive or negative pyroelectric peaks. The transformations from ferroelectric into antiferro- or paraelectric phases make positive pyroelectric peaks, and the transformations from antiferroelectric into ferro- or paraelectric phases make negative pyroelectric peaks. Suppose electrostatic potentials of various phases are different, then the relation between the orientation of pyroelectric peak and the type of phase transition could be explained properly. With the above relation the phase transitions with temperature variations in Pb(Zr,Ti)O3 antiferroelectric-ferroelectric materials can be defined.