A spring adjusting device and a valve assembly including the same. The spring adjusting device includes an adjusting screw rod, a spring, and a spring seat which is located between the adjusting screw rod and the spring. A groove is arranged in the spring seat, which can contain an end part of one end of the adjusting screw rod, and is provided with a cylindrical side wall. The spring adjusting device can prevent the end part of the adjusting screw rod from being separated from the groove, and the spring from being bent on the whole, thereby improving the overall working performance of the valve assembly.