:-Polypropylene is extensively used for varied applications due to its low cost, low density, high thermal stability and resistance to corrosion. Enhanced mechanical properties of Polypropylene can be achieved by mixing it with clays to form nanocomposites which increases its utility. Polypropylene Nano composites are formed by mixing polypropylene with calcium carbonate nano particles. This results in lighter materials with higher modulus and reduced linear thermal expansion making them desirable for some applications such as exterior automobile parts. The goal of this study is to determine thermo mechanical property ie Coefficient of Linear Thermal expansion of Polypropylene Calcium carbonate Nano composite using Thermo Mechanical Analyzer.