This paper proposed a wireless 16-channel im-plantable system for long-term neural recording. In order to achieve stable and reliable neural signal acquisition, the im-plantable microsystem consists of an analog front end (AFE), a transmitter (TX), a small battery and a coil for energy harvesting to charge the battery. The AFE integrates 16-channel low-noise amplifiers (LNA), a SAR ADC and a digital interface. The TX integrates a rectifier, a bandgap voltage reference, regulators and a 427 MHz OOK modulated transmitter. The AFE and TX chips were fabricated in 180-nm technology. All the required functional modules are integrated in the chips with off-chip crystal, coil and antenna. The proposed microsystem weighs 2.1 g without a battery, and 3.7 g including the battery. The dimension is $20\times 18\times 7$ mm 3. The total current of the system is 1.13 mA, and the battery life is about 50 hours with a capacity of 60 mA$h$. The charging current is 10mA under wireless power transmission.