In addition to the message service, the download service is another important business. The effective management and control of the download process is a prerequisite for stable operations for the business. The data integrity is the core content for download business. This article describes the content integrity check program in the download process of a mobile platform. It proposes a content integrity check strategy on the mobile platform based on Merkle tree, which reduces the cost of the integrity check effectively by shortening the size of checksum on the course of the network transmission. Theoretical analysis and the project has proven that the mechanism has high security connectivity and low network latency.