A valve core assembly and a valve adopting the valve core assembly. The valve core assembly comprises a valve core (4) and a transmission member (7) having a common axis, and a sliding ejector pin (6) arranged along an axis perpendicular to the common axis. The valve core assembly is disposed inside a valve body (1) and is rotatable about the common axis upon engaging with the valve body (1). The valve core (4) has one concave portion, and the transmission member (7) is at least partially placed inside the concave portion. A radial inwardly-convex profile (9) is formed at the circumferential wall inside the concave portion, the transmission member (7) is formed with a radial outwardly-convex profile (72), and when a valve rod (2) drives the sliding ejector pin (6) and the transmission member (7) to rotate, the radial inwardly-convex profile (9) in the concave portion of the valve core (4) engages with the sliding ejector pin (6) and the radial outwardly-convex profile (72) of the transmission member (7) to switch the valve core among an open state, a pre-closed state and a fully-closed state. The valve core assembly has a simple structure and a high space utilization, so as to minimize the size of the valve, and the opening torque is small and the sealing performance is desirable.