A gas-filled LED bulb manufactured by SMT includes a shell, a lamp holder, a holder, and a filament assembly. The shell defines a chamber therein. The lamp holder is positioned outside the chamber and assembled to the shell. The holder is secured in the chamber and fixed to the shell. The filament assembly includes a plurality of LEDs packaged in a SMD or CSP and a bendable circuit board. The LED is mounted on the circuit board by SMT and arranged on the circuit board sequentially, the circuit board has an elongated shape, and opposite ends of the circuit board are fixed to the holder.