In order to study the effect of high diameter ratio on the uniaxial compression performance of gangue cemented backfill body, five groups of cylindrical specimens with high diameter ratio of 0.5, 1, 2, 3 and 4 were prepared for uniaxial compression test, and at the same time, digital image correlation technology (DIC) and acoustic emission were used to monitor, and the stress curve, strain curve, apparent strain, acoustic emission ringing, energy and impact number of the backfill body were recorded, and the obtained data were processed and corresponded with each other with time, so as to explore the failure characteristics of different high diameter ratio backfill bodies. The results show that the peak stress and peak strain of gangue cemented backfill will decrease with the increase of the high diameter ratio, and have an exponential relationship with the high diameter ratio. The failure form of the backfill body changes from global failure to local failure after the high diameter ratio is greater than 2, and the local strain of more than 16% can lead to the overall instability of the backfill body. When the height to diameter ratio of the backfill body increased from 1 to 4, the damage degree for backfill body decreased to 11%. The proportion of damage of backfill bodies in the cumulative ringing count rapid rise region increased from 22.6% to 72.3% with the increase of the high diameter ratio, and the proportion reached 40.9% when the high diameter ratio was greater than 2, and the rising speed accelerated, and the concentration of damage was higher. the final cumulative ringing count of acoustic emission increases with the increase of the high diameter ratio at first, then begins to decrease after the high diameter ratio is 2, and the high diameter ratio has a great influence on the position of ringing concentration. The ratio of acoustic emission energy to ringing count (E/C) reacts to the intensity of energy release, the average E/C increases from 1.26 to 2.76 with the increase of the high diameter ratio, the rising speed of E/C before the peak stress begins to decrease after the high diameter ratio is greater than 2, and after the peak stress, the E/C rises faster after the high diameter ratio and the high diameter ratio is greater than 2. There is an upper limit to the intensity of the failure of the backfill body before the peak stress, which reaches the maximum when the high diameter ratio is 3, and the failure process of the backfill body with the high diameter ratio greater than 2 is more violent after the peak stress. The test results can provide a reference for the selection of the high-diameter ratio of the backfill body in structural backfill mining.