About 30-40 minutes. Frozen corn takes longer to steam than normal corn, which takes about 20 minutes to steam. Frozen corn does not thaw, and the water will be locked in the corn, so it takes longer to evaporate when steaming, which takes about ten minutes. Therefore, frozen corn can be cooked by steaming for about 30~40 minutes. Less than this time, the corn particles are still hard and not cooked.