Abstract: Sex attractant for pine caterpillar(Dendrolimus tabulaeformis Tsai et Liu)—(Z,E)-5,7-dodecadien-1-ol(Ⅰ),(Z,E)-5,7-dodecadien-1-yl acetate(Ⅱ) and(Z,E)-5,7-dodecadien-1-yl propionate (Ⅲ)were synthesized via Wittig condensation reaction. Field trials were undertaken in Chinese pine fields in the suburbs around Beijing in the summer of 1980.The experiments showed that mixture of Ⅰ,Ⅱ and Ⅲ gave strong attractant activity to the male pine caterpillar.Some male moths were attracted to simple Ⅰ,but few males to Ⅱ or Ⅲ.