When I use the code below to test the rotation function, the 3dtiles model was disappeared ,and then I tested this in http://cesiumjs.org/Cesium/Apps/Sandcastle/index.html?src=3D%20Tiles%20Adjust%20Height.html&label=3D%20Tiles ,it's ok.
My 3dtiles Model was created by smart3d.
tileset.readyPromise.then(function (tileset) {
var cartographic = Cesium.Cartographic.fromCartesian(tileset.boundingSphere.center);
var surface = Cesium.Cartesian3.fromRadians(cartographic.longitude, cartographic.latitude, 0.0);
var offset = Cesium.Cartesian3.fromRadians(cartographic.longitude, cartographic.latitude, 0);
var translation = Cesium.Cartesian3.subtract(offset, surface, new Cesium.Cartesian3());
var v = [0.7, -0.7,0, 0.7,0.7, 0, 0, 0,1];
var m = Cesium.Matrix3.fromArray(v);
var rotationTranslationMatrix = Cesium.Matrix4.fromRotationTranslation(m, translation);
tileset.modelMatrix =rotationTranslationMatrix;
console.log(rotationTranslationMatrix);
}).otherwise(function (arg) {
console.log(arg);
});