I used 2 methods to import it all are failed.

gremlin> graph.io(graphson()).readGraph("import/test.json")
graph.io(IoCore.graphson()).readGraph("import/test.json");
But for the example graphson I can import it.

gremlin> graph.io(graphson()).readGraph("data/tinkerpop-modern.json")
Another issue is about update and delete vertices and edges?

Below is the failed GraphSON file example:
This is the reference :
https://github.com/tinkerpop/blueprints/wiki/GraphSON-Reader-and-Writer-Library
{
    "graph": {
        "mode":"NORMAL",
        "vertices": [
            {
                "name": "lop",
                "lang": "java",
                "_id": "3",
                "_type": "vertex"
            },
            {
                "name": "vadas",
                "age": 27,
                "_id": "2",
                "_type": "vertex"
            },
            {
                "name": "marko",
                "age": 29,
                "_id": "1",
                "_type": "vertex"
            },
            {
                "name": "peter",
                "age": 35,
                "_id": "6",
                "_type": "vertex"
            },
            {
                "name": "ripple",
                "lang": "java",
                "_id": "5",
                "_type": "vertex"
            },
            {
                "name": "josh",
                "age": 32,
                "_id": "4",
                "_type": "vertex"
            }
        ],
        "edges": [
            {
                "weight": 1,
                "_id": "10",
                "_type": "edge",
                "_outV": "4",
                "_inV": "5",
                "_label": "created"
            },
            {
                "weight": 0.5,
                "_id": "7",
                "_type": "edge",
                "_outV": "1",
                "_inV": "2",
                "_label": "knows"
            },
            {
                "weight": 0.4000000059604645,
                "_id": "9",
                "_type": "edge",
                "_outV": "1",
                "_inV": "3",
                "_label": "created"
            },
            {
                "weight": 1,
                "_id": "8",
                "_type": "edge",
                "_outV": "1",
                "_inV": "4",
                "_label": "knows"
            },
            {
                "weight": 0.4000000059604645,
                "_id": "11",
                "_type": "edge",
                "_outV": "4",
                "_inV": "3",
                "_label": "created"
            },
            {
                "weight": 0.20000000298023224,
                "_id": "12",
                "_type": "edge",
                "_outV": "6",
                "_inV": "3",
                "_label": "created"
            }
        ]
    }
}