Tor soro, an endemic fish from North Sumatera, has a high economic value. Environmental damage causes a decreasing of Tor soro populations and leads to the extinction of these fishes in their natural habitat. Cryopreservation is an efficient strategy that can be used to minimize the problem. The success of this approach depends on how effective it is. This study to evaluate the fertilization of Tor soro using post cryopreservation spermatozoa 48 hours. The sperms collected by stripping, followed by the dilution using soluble liquid (fish ringer methanol 10%+skim milk) 1:9 comparison. The concentrations of the skim milk that is used in 0%, 5%, 10%, 15%, 20%, and 25%. The equilibration was carried out at the 5°C for 10 minutes before, then it kept frozen at the temperature of -10°C for 48 hours. The sperm thawing was carried out at the 40°C for 1 minute and one hundred egg cells (±1 g) were fertilized using 1.5ml of post cryopreservation sperm. The ANOVA test showed there was a fertility percentage effect of the skim milk on the frozen sperm. The 10% skim milk give an optimum with the highest fertility of (p<0.05) with 91.25±2.22% and motility (p<0.05) in 10% with 82.90±1.40%.