In Elliptic Curve Cryptography (ECC)-based Key management Scheme, the pair of ECC public and private keys is generated for all nodes in Heterogeneous Sensor Network and each node forms a shared key with their communication neighbors to establish secured connection. In Elliptic Curve Cryptography, by using a Simple power Analysis (SPA), an attacker is able to recover some secret data. This type of attack is called Non-Differential side channel attack. We propose an efficient Key Management Scheme which prevents non-differential side channel attack by including the unified addition formula for point doubling and point addition to perform point multiplication in ECC.  The performance evaluation show that our key management scheme can achieve significant reduction on power consumption and Storage space requirement than previous schemes. It also minimizes communication overhead and provides reliability against node failures.