Several　Pt-theta-Al2O3　catalysts　with　similar　ultra-low　Cl　contents　were　used　to　investigate　the　influence　of　dechlorination　temperature　on　propane　dehydrogenation　reaction.　The　Pt-theta-Al2O3　catalyst　treated　at　a　highest　dechlorination　temperature　showed　a　lowest　propane　rate　and　propylene　selectivity.　The　scanning　transmission　electron　microscopy　showed　that　the　dispersions　of　Pt　nanoparticles　decreased　with　an　increasing　dechlorination　temperature.　The　temperature-programmed　reduction　analysis　showed　that　higher　dechlorination　temperature　could　lead　to　strong　interactions　between　the　metal　and　support,　making　it　difficult　to　reduce　Pt　nanoparticles.　The　temperature-programmed　oxidation　analysis　implied　that　more　coke　was　deposited　on　the　metal　for　catalyst　treated　at　higher　dechlorination　temperature.　The　Raman　spectra　and　the　H/C　ratio　showed　that　more　side-reactions,　such　as　cracking　and　severe　deep　dehydrogenation　reactions,　occurred　on　catalysts　treated　at　higher　dechlorination　temperatures.　Therefore,　the　lower　the　dispersion　of　Pt　nanoparticles　was,　the　stronger　the　metal-support　interactions　and　increased　side-reactions　would　be,　resulting　in　lower　catalytic　activity　for　Pt-theta-Al2O3　treated　with　higher　dechlorination　temperature.