It has been observed that the SMEs have become a crucial segment caused by majority of private sector in developing countries consists of SMEs. As a consequence, it is important to accelerate the growth of SMEs in order to gain sustainable development in this era. Many scholars have argued that the strategic planning is one of the salient factors which contribute to the performance of SMEs. However, the SME sector encounters so many difficulties which challenge their growth and the survival. The question to be answered is that how they can be protected. At this context it opens the rooms to think that; what are the best practices that they can adopt while engaging their businesses. Scholars argued that the strategic planning contributed to the success of the firms. Accordingly this study is aimed at studying the strategic planning practices in the manufacturing SMEs in Sri Lanka. Data were collected through structured questionnaire given to 275 owner/managers in manufacturing SMEs in Western province of Sri Lanka. Descriptive analysis found that the majority of manufacturing SMEs in Western province preparing formal plans. With respect to the time period engaged in strategic planning, majority of 29 percent SMEs are engaged in strategic planning 7-9 years category. Further, the researcher was interested to identify the basis of the strategic plans. Accordingly, 37 percent of owner/managers of SMEs use their knowledge and education as the basis in the preparation of strategic plans. Their main argument is that the unpredictability of the business is their major barrier to engage in strategic planning process.