Abstract:Abstract: Factors, which affect the protoplast formation of barnyardgrass (Echinochloa spp.) pathogen Drechslera monoceras, such as mycelium age, lytic enzyme concentration, osmotic pressure of stabilizer, pH value of buffer solution, digesting temperature, period and so on, were studied. Maximum yield (1×106/mL) of protoplast could be obtained with 42 h old mycelia by using 2% lywallzyme in combination with 2% cellulase which containing 0.7 mol/L KCl as osmotic stabilizer and digesting for 4 h at 30 ℃ in pH 4.4~5.8 condition. The regeneration rate of the protoplast cultured on the solid media containing osmotic stabilizer was 0.15%.