private headers = new Headers({'Content-Type': 'application/json'});

private url = 'localhost:3000/users/register'; 
constructor(private http: Http) { }

registerEmail(link:string , email: string , password: string): Promise<any> 
{
return this.http
  .post(this.url, JSON.stringify({email: email , password: password}), {headers: this.headers})
  .toPromise()
  .then(res => res.json().data)
  .catch(this.handleError);
}

用postman请求正常显示post请求