Cosmic Microwave Background (CMB) temperature anisotropies and polarisation measurements have been one of the key cosmological probes to establish the current cosmological model. The ESA’s PLANCK mission is designed to deliver full-sky coverage, low-noise level, high resolution temperature and polarisations maps. We will briefly review some of the key problem of the PLANCK data analysis, and we will present how sparsity can be used to analyze such data set, especially for learning how to separate the CMB from other sky components.