Distributed network-based data backup, recovery and deletion methods and a distributed network system thereof are provided. The methods include respectively establishing peer-to-peer connections between a host storage server and a plurality of peer storage servers, dividing original data into a plurality of data segments, generating a plurality of data segment copies corresponding to the data segments according to a minimum survival rate and the number of peer storage servers. The methods also include transmitting the data segment copies to the peer storage servers, wherein the number of data segment copies for each of the data segments is equal to a redundancy, and the redundancy is smaller than the number of the peer storage servers, and the data segment copies distributed to any one of the peer storage servers correspond to a portion of all the data segments. Accordingly, the methods can effectively and safely backup the original data.