The invention discloses a preparation method of 1,1,1,3-tetrafluoropropene. The method comprises the following steps of: filling a fluorination catalyst into the front end of a reactor I and filling a Pd / AlF3 / C catalyst into the back end of the reactor I, wherein the volume ratio of the fluorination catalyst to the Pd / AlF3 / C catalyst is (3-1):(1-2); filling a Pd / AlF3 / C catalyst into a reactor II; reacting 1,1,2,3-tetrafluoropropene with
fluorine hydride gas in the reactor I in the
molar ratio of 1:(10-50) at the temperature of 250-400 and the air speed of 600-1,000 h<-1> under the normal pressure, and feeding produced
fluorine hydride, HCFC-1233xf,
chlorine hydride and HFO-1234ze into a separating
tower 2; feeding separated HCl and HFO-1234ze into a rectifying
tower; feeding HF and HCFC-1233xf into a separating
tower 3, feeding the separated HCFC-1233xf and a part of HF into the reactor II in the
molar ratio of 1:(5-45), reacting at the temperature of 250-400 DEG C and the air speed of 600-1,000 h<-1> and under the normal pressure, and circulating
tail gas to the separating tower 2; and separating gas entering the rectifying tower through the rectifying tower, separating a fraction HCl and other side products out, washing HFO-1234ze with alkali,
drying and packaging. The method has a simple process flow, and the selectivity of 1,1,1,3-tetrafluoropropene is high.