In the first category, four people are divided into three groups and 1 individual * * *, and then two groups of people stand on one of the seven steps, including

C(4,1) × a (7,2) =168 different station method;

In the second category, four people are divided into two groups, two people in each group, and then the two groups stand on one of the seven steps, including

C(3,1) × a (7,2) =126 Different station methods;

In the third category, four people are divided into three groups: 2 people, 1 person and 1 person * *, and then these three groups stand on one of the seven steps, including

C (4,2) × A (7,3) =1260 different station method;

In the fourth category, four people stand on one of the seven steps, with a (7,4) = 840 different standing postures;

So there are168+126+1260+840 = 2394 different station methods.