Heat shock protein 70 (HSP70) widely responds to stress environment and plays an important role in the promoting tumor cell apoptosis and in the control of normal mitosis growth of human cells. However, the physiological function of HSP70 start later in plant than in animal. Recent researches revealed that plant HSP70 is primarily involved in folding and maturation of nascent peptides, protein transporting, and the degradation of damage protein. Plant HSP70 plays an important role in environmental stress response, disease resistance, and development. This paper discussed the molecular functions of HSP70 in enhancing the plant stress tolerance, and systematically reviews latest progresses on molecular mechanism of plant HSP70 as well as improvement of plant resistance to facilitate broaden work.