This study was to explore the new GH134 family mannanase and its application potential for synergistic preparation of konjac mannan oligosaccharides with heterogeneous hygrothermal technology. In this paper， a new GH134 family mannanase (RmMan134B) was successfully obtained from the genome of Rhizopus microsporum GZHF10， which encoded 181 amino acids and a stop codon. The sequence identity with the reported GH134 mannanse was low (<69.6%). So the E. coli PET expression system was used for heterologous expression and property analysis， and the results showed that the most suitable substrate for the enzyme was konjac mannan， and the optimum temperature and pH were 40 ℃ and 5.0. Amorphophallus konjac powder was subjected to heterogeneous hygrothermal treatment at 115 ℃ and 0.1 MPa. The structure and properties of konjac were changed significantly. After 2 h of treatment， the apparent viscosity (30 g/L) of the solution of konjac flour was reduced 96.1%， the particle size of the powder was reduced， the thermal stability was improved， and the hydrolysis rate of the modified konjac flour was increased by 0.6-1 times. Further study found that the main components of RmMan134B enzymatic hydrolysis products are monosaccharides (0.922 mg/L)， disaccharides (1.4 mg/L) and trisaccharides (0.613 mg/L). This research had a certain role in promoting the efficient utilization of konjac mannan resources and the development of industrialization.