As an emerging network, Delay Tolerant Mobile Sensor Network (DTMSN) is susceptible to be attacked because of its limited resources and intermittent connectivity. Though authentication technology is usually used to prevent network from attacks, it is a challenging work in delay tolerant circumstance. In this paper, a node mutual authentication scheme based on Physical Unclonable Function (PUF) is proposed for DTMSN. We take advantage of the physical characteristics of chips with PUFs to prevent sensor nodes from cloning. Analysis indicates that the scheme is efficient and robust against different attacks, such as clone attack, replay attack, tampering attack, etc.