Waqf is one of Islamic philanthropy that teaches the basics of justice and benefit. Endowments as well manage the development of management innovations such as the presence of cash and productive endowments that have a positive impact on society. Furthermore waqf fundraising also utilize modern methods such as cash waqf auctions. Cash waqf auctions can be used as a supporting instrument to fulfill the requirement of the general public and education. In addition, waqf is not limited to the utilization as zakat, so that civilization construction programs can be carried out by waqf auctions funds. As it was carried out by Al-Azhar University and Pondok Modern Darussalam Gontor. The location used in this study is the Trensains Sragen Islamic Boarding School which utilizes the Fundrising waqf auction as an instrument for the construction of civilization. Therefore the purpose of this study is to find out the implementation of cash auction waqf at the Trensains Islamic Institution. To find out Islamic legal review of cash auction waqf at the Trensains Islamic Institution. This research is field research that uses a qualitative approach. In this study, the data was taken by interviews, observation, and documentation known as triangulation. Then the data is processed by Descriptive, Analysis and Comparative methods. The implementation of waqf in the Trensains Islamic Boarding School is similar to the practice of waqf in general. What’s interesting is to introduce the public to the development of the waqf system. Trensains educates waqf and opens a Service Office (KL). In the practice of waqf, the Trensain Islamic Boarding School had previously purchased land using bank funds. And for repayment, Treansain auctioned waqf by publishing waqf certificates of 300 per meter and announced using several media. Endowments are carried out together. This is done so that all Muslims can carry out waqf worship without waiting to become landlords. The practice of waqf in Islamic boarding schools is valid according to the provisions of Islamic law. However, based on statutory provisions, they have not met all the requirements. The problem is that the Trensains Islamic Boarding School should immediately register Nadzir in the Minister of Religion and Indonesian waqf Board through the Office of Religious Affairs. In this research the researcher still has many shortcomings, so it requires criticism and suggestions for the development of science. Key Word: Waqf, Establishment, Islamic Institution