public class KeywordController : ApiController {

[System.Web.Http.HttpPost]
public bool Post(KeywordInfo obj) {
　　var v = obj.SearchWord;

　　return true;

}

}

public static async Task<string> PostAsync(string url, object obj) {
using (var content = new StringContent(obj.ToJson())) {
var response = await _client.PostAsync(url, content);
response.EnsureSuccessStatusCode();
return await response.Content.ReadAsStringAsync();
}
}

HttpClientHelper.PostAsync("http://localhost:8098/api/keyword", new KeywordInfo { SearchWord = word });

POST方法断点断不到，似乎参数没有接收到。