We present a novel method to analyse swarm robotics sys- tems based on Bio-PEPA. Bio-PEPA is a process algebraic language originally developed to analyse biochemical systems. Its main advantage is that it allows different kinds of analyses of a swarm robotics system starting from a single description. In general, to carry out different kinds of analysis, it is necessary to develop multiple models, raising issues of mutual consistency. With Bio-PEPA, instead, it is possible to perform stochastic simulation, fluid flow analysis and statistical model checking based on the same system specification. This reduces the complexity of the analysis and ensures consistency between analysis results. Bio-PEPA is well suited for swarm robotics systems, because it lends itself well to modelling distributed scalable systems and their space-time characteris- tics. We demonstrate the validity of Bio-PEPA by modelling collective decision-making in a swarm robotics system and we evaluate the result of different analyses.