The group analysed dishes from six Chinese restaurants and found that 97% of them contained at least two grams of salt per dish.
Some 58% had more than three grams of salt per dish, half of the daily recommended maximum for an adult.
If people were to eat a side dish as well, they would be likely to exceed the six gram per day limit in one meal, the group said.
The group also looked at Chinese ready meals from supermarkets and found that, of the 141 examined, 43% were high in salt – high enough to receive a red warning label on the front of the pack.
Graham MacGregor, professor of cardiovascular medicine at London’s Queen Mary University and chairman of Action on Salt, called on health bodies to take immediate action.
He said: “Salt is the forgotten killer as it puts up our blood pressure, leading to tens of thousands of unnecessary strokes, heart failure and heart attacks every year.
“Reducing salt is the most cost effective measure to reduce the number of people dying or suffering from strokes or heart disease.”
Dr Alison Tedstone, chief nutritionist at Public Health England, said: “Our salt consumption has decreased over the last decade – a loaf of bread has 40% less than it used to.
“However, some products are still too high in salt and we know this can be reduced further.