The present work contributes to the difference between mechanical properties of lightweight cement mortar by using common waste such as coconut shell powder, wood waste and sea shell powder as the partial replacement of sand. These waste material can be found easily and I tried to make better use of them in this present work. The mechanical properties conducted were workability, compressive strength test and split tensile strength test. The results were concluded by describing the best material for replacement of sand and its optimum quantity which is to be added to produce light weight cement mortar. Lightweight cement mortar can be used in cases of underwater construction, for better heat resistance, eco-friendly construction. In, by and large, the mortar is plastic liquid-like structure comprises of OPC cement or Ordinary Portland Cement, water and Fine aggregate. The common mortar can be used for masonry works in most of the cases. But to impart special characteristics to the common mortar we need to add some ingredients such as fly ash, rice husk ash, metakaolin, etc. So, in this present work, I used different waste material as partial replacement for the fine aggregate or sand.