Targeting the low efficiency and privacy leakage of intra-city delivery of confidential documents， a intra-city path planning algorithm based on block-chain is proposed. It adaptively generates the shortest path to protect location privacy in real time. With the consensus mechanism and smart contract algorithm of block-chain， the distributed site is selected by route planning with homomorphic encryption. The vehicle can encrypt and decrypt the next site information by using its own context attribute， and be equipped with anti-impersonation. This algorithm also solves the problem of mutual distrust among vehicles， sites and deliveries. Finally， through experiments， the impact of the homomorphic calculation results of smart contracts， the number of different contextual attributes， and the number of different sites on the calculation cost of path planning is analyzed. The results show that the algorithm of the intracity delivery system has the capabilities of confidentiality， integrity and anti-tampering and can ensure high-delivery efficiency.