Want to transit through Beijing for Mongolia (Ghaus ur Rahman, Pakistan)

I am Ghaus ur Rahman completed PhD in Mathematics. My application have been accepted by CIMPA, Nice France to attend Research School ''Functional Analysis and Partial Differential Equations'' in Mongolia 17-28 July 2017. CIMPA will provide me air ticket, stay in Mongolia, food will be provided during the research school and exempted me from registration fee (letter have been issued to me by CIMPA France,).
Mongolia issue VOA as there is no embassy of Mongolia in Pakistan. I have invitation letter from local organizers and a letter in which they mentioned that my particular are sent to immigration office at Chinggis khaan international airport, Ulaanbaatar so that I will get VOA at Ulaanbaatar.
If I transit at Beijing airport and if my stay at Beijing airport is less than 24 hours then will I need China transit visa?
Looking forward to hear soon from you. Thanking you in anticipation.
Profound Regards
Ghaus ur Rahman(PhD Mathematics)
Mingora, KPK, Pakistan.