Abstract : Blockchain is a Peer to Peer decentralized and distributed ledger system that records transactions across multiple computers or nodes in a secure, transparent, and immutable manner. Blockchain is quickly getting evolved from application like crypto currencies to health care systems. In Blockchain technology, each user has their own blockchain. Transactions are recorded in blocks which are main component of blockchain. Typically, the size of block is not more than 1MB. New blocks are created when an existing block is full. Blocks are connected with hash value. Each block will have the header information which consists of hash value of previous block and hash value of the current block. When a transaction executes, the blocks of all blockchains in the peer-to-peer network updates and new block hash value is generated. So, it's nearly impossible to tamper transaction details because this yields to update hash values of almost all blocks of whole blockchain in entire peer to peer network. Each time transaction is added to a block, a Merkley tree which is also called as Hash tree is constructed to generate Block hash. It is very important to generate block hash value in fast and secured manner. In this paper, Both SHA1 and SHA256 algorithms are used to construct advanced Hash tree. We took the advantages of both secure hash algorithms mentioned above and We used multi-threading to generate hash tree data structure to quickly produce block’s final 256-bit hash value. The experimental results showed that this work can quickly produce block’s hash value when compared to conventional approach without compromising the security metrics Avalanche effect and Collision resistance.