The rock acoustic emission(AE) under five kinds of different end effect was study using numerical simulation code RFPA2D.The relationship between end effect and rock acoustic emission under five elastic modulus ratios(EP/Es) of clamping plank and rock specimen were discussed.The time sequences and space distribution law of AE were got,i.e.,when EP/Es<1,a few high frequency AE occurred and mainly at the two ends but few at the middle of rock specimen;when EP/Es=1,only one high frequency AE occurred and random uniformity at whole rock specimen;when EP/Es>1,numbers of high frequency AE occurred and mainly at the middle of rock specimen.The characters and laws offer good references for avoiding the influence of clamping plank on the failure process of rock specimen during compression test of rock with press machine.