Why beam elements length are larger than Hmin?

CTRL MESH 1 HMIN 1

The resulting beam elements are all about 4.6m, are they suppose to be <=Hmin (1m)?

I’m assuming you are using sofimshC.
Ctrl Hmin is a global control.
Check the definition of your beam elements so there isn’t a local mesh definition that contradicts it. (Sln Sdiv)

yes, it’s sofimshC
No local mesh definition

SLN NO NPA NPE REF GRP STYP SNO
101 100 101 AXIS 1 B 1
102 101 102 AXIS 1 B 1
103 102 103 AXIS 1 B 1