To improve tumour accumulation and enhance cellular uptake,targeting ligands were grafted onto drug-loaded nanoparticles to endow them with active targeting ability[1].It seems that the "shieldable targeting strategy" could significantly enhanced the stability of nanocarriers in the blood circulation and the accumulation of drugs in tumour tissues.Unfortunately,less than 5%of the injected dose could be delivered to the tumour sites [2] due to the abnormal architecture and composition of the tumours,shch as the leaky tumor blood vessels and the elevated interstitial fluid pressure(IFP)[3,4].Some nanopartcles are pumped out from the tumor cell after celluar uptake,and be quickly eliminated due to the ligands exposed on the surface.