Traditional Littrow-type ECDL has a collimating cavity which is sensitive to the external vibration. To solve this problem, we demonstrate a high-stability Littrow-type ECDL by using a non-collimating cavity. The laser has a maximum output power of 30.2mW at 420mA drive current. The 3dB tuning range of the laser is more than 100nm covering all C-band. Compared to the ECDL using a collimating cavity, the RMS power stability is improved from 0.52% to 0.02% and the peak-to-peak power stability is improved from 3.6% to 0.1%. The integral linewidth is suppressed from 51.5kHz to 15.4kHz and the intrinsic linewidth is 2.2kHz with 75mm cavity length. By prolonging the cavity length, the intrinsic linewidth can be reduced to 31Hz. This paper presents a simple structure to substantially improve the power stability of ECDLs and reduce the linewidth to Hz level.