Abstract: The speed of sound in asymmetric nuclear matter with SG Ⅱ-type potential (including SG Ⅱ and RATP potential) is calculated. We find that the spin exchange part of SG Ⅱ-type potential cannot avoid the difficult of superluminosity. The effect of finite-range force fot the speed of sound is very small. The violation and the restoration of causal condition are discussed.

Key words: the speed of sound in asymmetric nuclear matter, zero-range force finite-range force, causal condition