Fresh weight, water content, chlorophyll a, b and carotenoid content of Poa pratensis L.are recorded and compared at different times after 0(control), 116.50, 138.20, 161.30 kg/hm² KNO₃ fertilizer is applied to explore fertilization methods for a robust growth of Poa pratensis L.in Daqing, Heilongjiang.The result shows that the fresh weight ofPoa pratensis L.increases with KNO₃ fertilizer, 161.30 kg/hm² treatment is significantly higher(P<0.05)than that of control group, the water content of Poa pratensis L.plant is higher than that of control group in 116.50 to 161.30 kg/hm² treatment when in June and October and the 161.30 kg/hm² treatment is significantly higher(P<0.05)than that of control group in July and August.Throughout the test, 161.30 kg/hm² treatment’s chlorophyll a, b and carotenoid content are significantly higher than that of the control group.Therefore, it is safe to come to a comprehensive analysis, that is, the 161.30 kg/hm² treatment can significantly improve the bluegrass growth traits.