This paper reviews previous methods for measuring the microbial biomass P in soil,with comments on their problems and limitations in the use for different soil types,and described main procedures involved in the measurement.A study was carried out to validate the methods for upland soils in China.Results show that for the 45 soils used,the flush of inorganic P(P_i)extracted in 0.5 mol L^-1 NaHCO₃ (pH8.5) at a soil solution ratio of 1:20 following gaseous chloroform-fumigation,as proposed by Brookes et al.^[4], provided a better indication of the amount of the biomass P than that extracted at a lower soil solution ratio (1:4),or in 0.03 mol L^-1 NH4F-0.025 mol L^-1 HCl at both the ratios(1:4 and 1:20).In most of the soils,the size of the flush of P_i was not significantly different from that of the flush of total P extracted (P_t),suggesting that the measurement of P_t was not necessary.