This study is to suppress the cell voltage and arm current in modular multilevel converters (MMCs) based on power balancing and current tracking control law. MMCs have been widely applied to direct-current transmission, high-voltage grid power injection, back-to-back power transfer, energy storage systems and renewable energy systems. In particular, the renewable energy systems have been depicting a lot of prospect due to low pollution, natural replenishment, large capacity, and sustainable development. The dimension of each cell capacitors and the rating of switches play a critical part in designing an MMC, and cell voltages highly interact to arm currents, dc circulation currents and grid-injection currents. Normally, higher arm current require lower cell-voltages when adopting a zero-mean current injection technique. This paper presents unique approaches to deriving cell-voltage expression in terms of arm currents, injected zero-mean current and current tracking control laws, on which cell-voltage ripple reduction and arm-current swing suppression can be achieved. Simulation results obtained from a 10 kW single-phase MMC have verified the analysis and discussion.