The invention relates to an instrument installation structure for a concrete prism test. The instrument installation structure is divided into two groups. The two groups of the instrument installationstructure are symmetrically arranged outside two sides of a concrete prism test block. Each group of the instrument installation structure includes an upper seat block, a lower seat block, an instrument installation plate and an instrument contact seat, wherein the inner sides of the two seat blocks are respectively welded with steel connecting pieces inserted into the concrete prism test block so as to enable the two seat blocks to form fixed connection with the concrete prism test block, and the outer sides of the upper seat block and the lower seat block are reserved with bolt holes; the instrument installation plate is fixed at the outer side of the upper seat block through a bolt connected with the upper seat block, the instrument contact seat is fixed at the outer side of the lowerseat block through a bolt connected with the lower seat block, an instrument for testing is fixed at the outer side of the instrument installation plate through the bolt connected with the upper seatblock, and the tail end of a contact rod of the instrument for testing is contacted with the upper end of the instrument contact seat. The instrument installation structure is detachable, ensures thetest to be conducted smoothly and accurately and improves the deformation test accuracy of the concrete prism test.