Mycoplasma gallisepticum HS strain (MG-HS) is a pathogen that causes chronic respiratory disease (CRD) in chicken, which is characterized by host respiratory inflammatory damage, brings huge economic losses to the poultry industry.  Recently, emerging Chinese herbal medicines (CHM) have been used to treat CRD.  This study was aimed to investigate the preventive and therapeutic effects and their potential mechanisms of Chinese herbal medicinal formulae (CHMF), which consisted of 10 kinds of Chinese herbal medicine including Scutellaria, Houttuynia cordate and licorice, on MG-induced CRD in chickens.  With respect to the preventive effect, the results showed that CHMF could effectively recover the MG-induced decrease on body weight and feed conversion ratio.  Histopathological analysis showed that both prevention and treatment of CHMF could significantly alleviate the severe respiratory inflammation induced by MG infection.  Moreover, compared with the MG infection group, both the prevention groups and the treatment groups of CHMF could effectively reduce the expression of MG adhesion protein (pMGA1.2) to inhibit the proliferation of MG, and thus effectively inhibit the expression of MG-induced inflammatory factors interleukin-1β (IL-1β) and tumour necrosis factor-α (TNF-α).  In summary, these findings confirm that CHMF can protect chickens from various tissue damage caused by MG infection and has no adverse effects on the performance of chickens in the short term.  And its efficacy against MG is equal to or better than that of tiamulin.