Disclosed herein is a biaxially oriented paraphenylene sulfide block copolymer film showing a heat shrinkage of 0-2.0% at 100.degree.-220.degree. C., comprising a paraphenylene sulfide block copolymer essentially composed of recurring units (A): ##STR1## and recurring units (B): ##STR2## the molar fraction of recurring units (A) being 0.50-0.98, and having a melt viscosity (.eta.*) of 1,000-15,000 poises as measured at 310.degree. C. and shear rate of 200 sec.sup.-1, a glass transition temperature (Tg) of 20.degree.-80.degree. C., a crystalline melting point (Tm) of 250.degree.-285.degree. C. and a crystallization index (Ci) of 15-45 (measured with the non-stretched heat-treated polymer film), and a process for producing the biaxially oriented paraphenylene sulfide block copolymer film.