Trusted Execution Environment(TEE) is for ARM-based chips supporting TrustZone technology. NXP released LSDK integrates Open Portable TEE(OP-TEE), which is an open source project which contains a full implementation to make up a complete Trusted Execution Environment. This document will introduce OP-TEE architecture, OP-TEE OS loading and initialization, TA and CA communication in OPTEE runtime workflow, how to develop OP-TEE Trusted Application in LSDK environment.