The growing number of vehicle users is one of the factors that affect the increase in traffic volume, causing traffic problems called congestion such as at unsignalized intersection in the Selokan Mataram area, Sleman. Method used to assess the intersection performance with Highway Capacity Manual Indonesia 2014 and modeling with the PTV VISSIM 9 Student Version software at peak hours. Results of existing conditions with PKJI 2014 in the form of total traffic flow value = 3861,7 skr/hour, intersection capacity = 2888,961 skr/hour, degree of saturation = 1,337, delay = 848,219 sec/skr, and the chance of queue = 74 – 155 %. Seeing the results of the existing conditions, it can be assessed that the intersection performance does not meet the maximum degree of intersection (DJ ≤ 0.85). The results of the existing conditions with PTV VISSIM 9 Student Version modeling in the form of service level values are LOS (All) = LOS E and VehDelay (All) = 36,84 seconds, so that the intersection service level is said to be bad. Based on the results of the two methods it was found that using PKJI 2014 intersection performance conditions were still poor, as well as the level of service produced from VISSIM was also poor, so that the existing conditions of both methods still needed improvement efforts. Improvements are planned with 3 alternative traffic problems, with the best results, the third alternative is to shift the location of the median and traffic engineering, which produces DJ value = 1,029 with T = 14,452 sec/skr and LOS (All) = LOS C value with VehDelay (All) = 16,56 seconds. The results of exhaust emissions of existing vehicles show better results than alternative 3, this is because the number of alternative vehicles 3 is greater than the number of existing vehicle conditions.