In this paper, we present the baseband receiver design for IEEE 802.11ah. We study several key receiver algorithms, including coarse frequency offset estimation and coarse timing synchronization, fine frequency offset estimation, fine timing synchronization, channel estimation and MIMO equalization. For channel estimation, we propose to use decoded SIG field to improve its estimation. To further improve receiver performance in low SNR range, we propose phase tracking algorithm after MIMO equalization using pilot subcarrier and tentative data decision. Extensive simulations have been conducted to demonstrate receiver high sensitivity.