The invention discloses modified glass for thin-film solar cells, and a preparation method of the modified glass. The modified glass is prepared from the following components: silicon dioxide, aluminum oxide, sodium oxide, potassium carbonate, zinc oxide, borax, sodium borate, cobalt oxide, sodium chloride, graphite, manganese powder, quartz sand, nickel oxide, calcium oxide, chromium oxide, bamboo fibers, sodium hydroxide and an antioxidant. The preparation method comprises the steps of putting the silicon dioxide, the aluminum oxide, the sodium oxide, the potassium carbonate, the zinc oxide, the borax, the sodium borate, the cobalt oxide, the sodium chloride, the graphite, the manganese powder, the quartz sand, the nickel oxide, the calcium oxide and the chromium oxide into a reaction kettle, heating up to 500-700 DEG C, and then carrying out plasma treatment to obtain a first mixture; mixing the bamboo fibers with the sodium hydroxide, soaking the obtained mixture at low temperature for 24-34h, then adding the soaked mixture into the first mixture, adding the antioxidant, and evenly stirring to obtain a second mixture; sintering the second mixture at high temperature. After being modified, the glass is good in mechanical properties and high in surface stress, thus being suitable for serving as components of the thin-film solar cells.