Signal-to-noise ratio (SNR) estimation plays an important role to adaptive modulation in Evolved Multimedia Broadcast Multicast Services (eMBMS). Based on the knowledge that the received signal space consists of signal subspace and noise subspace, we propose a subspace-based SNR estimation solution to cope with the time-varying channel with frequency selective effect and different OFDM pilot structure situations in eMBMS. The simulation is carried out on both PC and Aeroflex PXI platform. Simulation results show this proposed method gives good performance with different eMBMS pilot length and time-varying channels.