It is a good idea to get in touch with expat communities in Beijing , you can google them online and try to get in touch ,there you would certainly meet many native English speakers.
I will give you some tips to improve your spoken English in general , among them will always be of course mingling and speaking with native speakers as much as you can ,whether in real life or online as a temporary solution for not finding native speakers in real life.
Observe the mouth movements of those who speak English well and try to imitate them.
When you are watching television, observe the mouth movements of the speakers. Repeat what they are saying, while imitating the intonation and rhythm of their speech.
* Until you learn the correct intonation and rhythm of English, slow your speech down.
If you speak too quickly, and with the wrong intonation and rhythm, native speakers will have a hard time understanding you.
Don't worry about your listener getting impatient with your slow speech -- it is more important that everything you say be understood.
* Listen to the 'music' of English.
Do not use the 'music' of your native language when you speak English. Each language has its own way of 'singing'.
* Use the dictionary.
Try and familiarize yourself with the phonetic symbols of your dictionary. Look up the correct pronunciation of words that are hard for you to say.