Blazars are the most promising sources of high energy emission in the known universe. They are a subclass of Active Galactic Nuclei (AGN) where the emission originates from a relativistic jet aligned at or close to the line of sight. Their broad band spectrum is predominantly non-thermal, extending from radio to gamma-ray energies. Blazars show very high flux variability across the electromagnetic spectrum. Here, we present a study of the long-term variability in radiation from the FSRQ 3C454.3 by constructing flux distributions using 10-year simultaneous optical and gamma ray observations from SPOL and Fermi-LAT, respectively. Also, we study flux distribution using X-ray data from AstroSat. We perform investigations of the temporal and spectral variability. As for the temporal analysis, we construct light-curves with the data from all the three bands. Further, we construct the Spectral Energy Distribution (SED) using X-ray data (LAXPC and SXT) and fit the SED with various models viz. power-law, log-parabola and broken power-law.