Abstract: The method of drilling fluid pulse transmission is mostly used in the wireless signal transmission system between downhole and surface.The transmission speed of signal is a basic parameter of the transmission method.This paper presents the calculating formula of drilling mud pulse transmission speed.and analyzes influences of drilling mud composition and properties,pipeline feature and drilling mud type on positive and negative pulse transmission speed.The conclusion of this paper is valuable for reference to the design and realization of wellbore trajectory automatic control system.