Because of the randomness of biometric features, traditional methods cannot perform well in the encryption of fingerprint template. The Fuzzy Vault construct is a biometric cryptosystem which can bind the fingerprint features with the secret key, and give reliable protection to both of them. The performance of Fuzzy Vault is highly affected by the alignment of fingerprints in the encryption field. In this paper, we propose a novel helper data based on the topo-structure around the core. The topo-structure has the advantage that it does not reveal any information about the template minutiae, and can reduce the alignment calculation amount. Experimental results show that the novel helper data has a good performance in alignment between vaults with high security.