Objective: To investigate the clinical value of dual-phase arterial spin-labeled perfusion imaging(3D-ASL) in the evaluation of collateral circulation compensation in patients with severe cerebrovascular stenosis. Methods: From December 2017 to August 2018, 73 patients with severe cerebral artery stenosis confirmed by MRA in Linfen Central Hospital were collected and studied.The two-phase superconducting magnetic resonance imaging was performed[Post Label Delay(PLD): 1 525ms, 2 525ms] three-dimensional quasli continuous arterial spin labeling(3D-PCASL) imaging.Bilateral phase cerebral blood flow(CBF) was measured on the affected side and mirror side respectively.The CBF values of the affected side and mirror side were compared and analyzed, and the abnormal perfusion cases were compared and analyzed. Results: In 73 patients with severe cerebrovascular stenosis, the CBF values of the bilateral affected side[CBF 1 525ms(18.33±6.42)mL·100g^-1·min^-1, CBF 2 525ms(34.81±11.68)mL·100g^-1·min^-1] were lower than those of the mirror side[CBF 1 525ms(41.25±16.84)mL·100g^-1·min^-1, CBF 2 525ms(47.74±14.90)mL·100g^-1·min^-1], the differences were statistically significant(Z=-9.348, -7.476, all P<0.001). The ratio of abnormal perfusion in PLD=2525ms group[CBF(34.81±11.68)mL·100g^-1·min^-1]was higher than that in PLD=1 525ms group[CBF(18.33±6.42)mL·100g^-1·min^-1], the difference was statistically significant(Z=-9.196, P<0.001). The percentage of abnormal perfusion in PLD group of 2 525ms(56.2%) was lower than that in PLD group of 1 525ms(94.5%), the difference was statistically significant(χ²=5.393, P=0.02). Conclusion Dual-phase ASL(PLD=1 525ms, 2 525ms) combined with ASL can more accurately evaluate the compensations of fast collateral circulation and slow collateral circulation, and provide individualized treatment.