The invention relates to a battery replacement device applicable to an electric vehicle, which comprises a battery box turntable group, a charging rack battery taking and placing device and an electric vehicle battery taking and placing device, wherein the battery box turntable group comprises a plurality of battery box turntables arranged in a line, and the battery box turntables can rotate witha certain angle around axes per se; the charging rack battery taking and placing device is arranged between the battery box turntable group and a charging rack; and the electric vehicle battery taking and placing device is arranged between the electric vehicle and the battery box turntable group. The invention also relates to a battery replacement system with the battery replacement device. In the battery replacement device, two types of battery taking and placing devices are used to be matched with the turntables to ensure that the battery box replacement of the electric vehicle becomes smoother. The entire battery replacement process is smooth and short in time. Because the efficiency of battery replacement is increased, more battery replacements can be completed within unit time, the battery replacement period is shorter, so that a charger can charge completely, and the utilization rate is higher.