Many organizations have begun reassessing their use of traditional relational databases in reaction to this deluge of data. Modern database like NoSQL is getting used to manage this kind of structured and non-structured large amount of data. Consequently, there was a need to transform the database from traditional to modern fashion. Database administrators encounter frequent problems when switching from relational to modern models since NoSQL is a very flexible and different database than relational database. Many methods for transforming relational databases into NoSQL models have been developed at logical and physical level. But there are a smaller number of studies conducted at conceptual level for conversion between relational and NoSQL databases. Conceptual level data modelling is incredibly significant for every database. There is still need for a transforming approach at conceptual level which can be common for all types of NoSQL models. The objective of our research is to conduct a literature survey and propose a standard and unique approach for model-to-model conversion from traditional relational databases to modern NoSQL database at conceptual level. Our aim is to simplify the transformation process. This method leverages consistency and simplicity and works with all NoSQL types. By offering a formal method, this study attempts to close the gap between relational and NoSQL database design, assisting database designers and developers who are moving to NoSQL environments.