Abstract: Coal water slurry (CWS) with high mass concentration, as a kind of uniform suspension, has the property of non - Newtonian fluid, and there is a slip phenomenon when it flows in pipe. The similitude criterion, known as general Reynolds number Reg which can characterize the state of CWS flow in pipe, was put forward on the basis of analyzing the flow of the slip layer of CWS in pipe. The results show Reg holds good not only for the slip flow of CWS with the properties of general Bingham or Bingham fluid,but also for the no slip flow of other non -Newtonian fluid and Newtonian fluid. Moreover, for the non -Newtonian fluid of CWS consisting of water, coal powder and the chemical additives, the equation of the energy loss coefficient of CWS laminar flow in pipe has the same form as Newtonian fluid, that is λ=64/Reg. Compared with the experimental data, the accuracy of the equation is satisfactory in the experimental range.