5G IoT communications have some new requirements on the whole system design, e.g., low cost, low power consumption, long distance coverage and massive connection. To fulfill all these requirements, a narrow-band SCMA scheme is proposed. Narrow band pulse shaping is employed, so that the coverage can be expanded with low-cost and low-power devices. Two types of waveforms are provided, both of which use SCMA to enlarge the number of supported devices. Simulation results show that, comparing to the existing narrow band techniques, narrow-band SCMA scheme can support more dense connectivity without any other performance degradation.