FIELD: medicine； pharmaceuticals.SUBSTANCE: invention relates to a new yonkenafil type A polymorph (monohydrochloride 2-[2-ethoxy-5-(4-ethylpiperazine-1-sulfonyl)phenyl]-5-methyl-7-n-propyl-3,7-dihydropyrrole[2,3-d]pyrimidin-4-one), possessing the properties of a phosphodiesterase type 5 inhibitor (PDE-5), a method for its preparation, a pharmaceutical composition based on it and its application. Polymorph is used to produce a drug to treat or prevent erectile dysfunction in a male animal and diseases associated with phosphodiesterase type 5. Type polymorph has diffraction peaks on a powder diffractogram with three or more values 2θ, selected from: 8.4 ± 0.2°, 11.3 ± 0.2°, 13.9 ± 0.2°, 14.2 ± 0.2°, 14.7 ± 0.2°, 16.8 ± 0.2°, 17.1 ± 0.2°, 19.7 ± 0.2°, 21.0 ± 0.2°, 21.7 ± 0.2°, 22.4 ± 0.2°, 23.3 ± 0.2°, 23.8 ± 0.2°, 26.8 ± 0.2°, 27.5 ± 0.2°, 28.0 ± 0.2°. Polymorph cell parameters are essentially the following: cell size: a (Å) is 19.1 ± 0.1； b (Å) is 12.7 ± 0.1； c (Å) is 11.3 ± 0.1； volume is 2741 ± 30 Å3； space group is a P21/s； density is 1.31 ± 0.01 g/cm3. Thermogram of the differential scanning calorimetry of the polymorph contains endothermic peaks at 34–133 °C and 231–250 °C, respectively, preferably endothermic peaks at 86.4 °C and 237.9 °C respectively. Method of obtaining polymorph type a of yonkenafil hydrochloride includes: suspending yonkenafil hydrochloride in water or water with alcohol, heating with dissolving yonkenafil hydrochloride, slow cooling and crystallization, filtering with collecting solids and drying to obtain polymorph type A of yonkenafil hydrochloride or achieving equilibrium when dissolving yonkenafil hydrochloride in water or water with alcohol, filtering and drying to obtain yonkenafil hydrochloride type A polymorph. Alcohol is preferably selected from ethanol or methanol or a mixture thereof. Typically, the volume ratio of alcohol to water is from 95:5 to 0:100. Heating temperature ranges from room temperature to 90 °C. Slow cooling is
