Abstract: In this paper, the characteristics and models for indoor time-varying clusters at 26 GHz are studied based on large scale single input multiple output (SIMO) measurements. The algorithm for finding clusters in METIS (Mobile and Wireless Communications Enablers for the Twenty-twenty Information Society) project was improved. In order to remove the effect of the rays in a cluster and the noise, the envelope for a power-delay-profile (PDP) is calculated before counting number of clusters, which is good to get a more reasonable result. Based on the measurement, the variation of number of clusters with time is modeled as a normal distribution with the mean and variance to follow a quadratic function with respect to the time intervals.