In order to study the strain rate effect and size effect during the brittle failure process of ice under uniaxial tension and compression with numerical means, particle-subdomain method (PSM) is introduced. PSM is a continuum-discontinuum coupled method with time-dependent explicit algorithm of dynamic relaxation, which has combined the advantages of particle-in-cell method, finite element method and discrete element method. The governing equation of this method is deduced from Lagrange equation, which is a unification of expression for continuous deformation, fracture and failure. The complex failure behaviors of brittle ice under uniaxial tension and compression in laboratory scale are simulated. The progressive failure process with fracture evolution can be well described with this method. The results show that failure mode and the strength of ice material are affected by loading rate, boundary conditions and the size of the specimen. The strain rate effect and size effect with transition property are naturally obtained and can be explained with internal fracture evolution process within the material. (c) 2020 Published by Elsevier B.V.