This study is concerned with the sensor fault estimation problem for network-based vehicle suspension system with deny-of-service attack, where a linear robust observer is designed. First of all, the attack behaviour switching is modelled as a Markovian jumping process, and then a sufficient condition based on the Markovian jumping system approach is proposed such that the sensor fault estimation error system is asymptotically stable in the mean-square sense with a prescribed H ∞ performance level. In this work, the occurring and transition probabilities of the attack are allowed to be partially unknown and uncertain. Finally, a simulation example is presented that validates the effectiveness of design method.