An apparatus with a reagent container for performing polymerase chain reaction or reverse transcriptase polymerase chain reaction (RT-PCR) by thermal convection, wherein said reagent container comprises reactants and reagents, said reagents comprises a fluorescence material or a probe, characterized in that the apparatus comprises: a first bracket, disposed on a horizontal plane, wherein the first bracket comprises a first perforation; a second bracket, disposed below the first bracket and parallel to the horizontal plane, wherein the second bracket comprises a second perforation, and the second bracket has a bracket upper surface and a bracket lower surface, wherein the bracket lower surface of the second bracket further comprises a retaining groove, the retaining groove is parallel to the horizontal plane and the retaining groove connects the second perforation; a temperature sensing device, disposed in the retaining groove, wherein the temperature sensing device comprises a glass, a temperature sensor and a contact node, wherein the glass has a film upper surface and a film lower surface, and a transparent conductive film is disposed on the film upper surface or the film lower surface, the size of the glass is equal to the size of the retaining groove so the glass can be fixed into the retaining groove by the film upper surface or the film lower surface, the contact node is disposed at the same side of the transparent conductive film, the temperature sensor is disposed on the film upper surface or the film lower surface and is configured to measure the temperature of the transparent conductive film; a power supplying device, comprising a power supply and a power regulator, wherein the power supply supplies power to the contact node so the temperature sensing device can perform a heat process, and the power regulator is configured to control an output current; a light source, configured to excite the fluorescence material or the probe; a light receiver, configured to detect or receive a fluorescence signal; a processor, configured to process and regulate system; and an accommodation space, disposed between the first bracket and the second bracket and is configured to accommodate the reagent container, wherein the reagent container is placed into the accommodation space through the first perforation and further through the second perforation and the retaining groove to contact the film upper surface of the glass, wherein the power supply provides current to the contact node to heat up the glass. a first bracket, disposed on a horizontal plane, wherein the first bracket comprises a first perforation; a second bracket, disposed below the first bracket and parallel to the horizontal plane, wherein the second bracket comprises a second perforation, and the second bracket has a bracket upper surface and a bracket lower surface, wherein the bracket lower surface of the second bracket further comprises a retaining groove, the retaining groove is parallel to the horizontal plane and the retaining groove connects the second perforation; a temperature sensing device, disposed in the retaining groove, wherein the temperature sensing device comprises a glass, a temperature sensor and a contact node, wherein the glass has a film upper surface and a film lower surface, and a transparent conductive film is disposed on the film upper surface or the film lower surface, the size of the glass is equal to the size of the retaining groove so the glass can be fixed into the retaining groove by the film upper surface or the film lower surface, the contact node is disposed at the same side of the transparent conductive film, the temperature sensor is disposed on the film upper surface or the film lower surface and is configured to measure the temperature of the transparent conductive film; a power supplying device, comprising a power supply and a power regulator, wherein the power supply supplies power to the contact node so the temperature sensing device can perform a heat process, and the power regulator is configured to control an output current; a light source, configured to excite the fluorescence material or the probe; a light receiver, configured to detect or receive a fluorescence signal; a processor, configured to process and regulate system; and an accommodation space, disposed between the first bracket and the second bracket and is configured to accommodate the reagent container, wherein the reagent container is placed into the accommodation space through the first perforation and further through the second perforation and the retaining groove to contact the film upper surface of the glass,