The vast majority of the victims were in Zhengzhou, the provincial capital, where 292 died and 47 are missing.
Residents cleared away mud, wrecked cars and other debris after record rains that started Tuesday and flooded streets and disrupted train service.
The torrential rains, the heaviest in 1,000 years, have affected about three million people in Henan province.
Streets have been turned into rivers and people were stranded in apartments, offices, hotels and rural homes in dozens of cities and towns.
25 killed, over one million affected as unprecedented floods hit central China; President Xi calls in PLA
Xi ordered the deployment of the People's Liberation Army and said that authorities at all levels must give top priority to ensuring people's safety and property.