The invention relates to a solid amalgam material, in particular to an indium-sn-bismuth-amalgam used for the small tube diameter which is used for a low pressure mercury discharge lamp and simultaneously satisfies the following characteristics: 1. the melting temperature is higher than or close to the maximum working temperature of delta T95; 2. for lamp tubes with the diameters phi less than 10mm, the working temperature region is 90-133 DEG C, and the delta T95 is more than 30 DEG C; 3. lead is not contained; and 4. the mass content of mercury is maximized under the premise of ensuring theperformance, and the indium-sn-bismuth-amalgam has low use cost and is easy to place. The indium-sn-bismuth-amalgam contains the following components according to mass content: 58-66% of bismuth, 25-32% of sn, 6.4-9.5% of indium and 1.6-2.8% of mercury, wherein the mass ratio of the bismuth (Bi) to Sn is more than 1.85. Lamps using the amalgam have high luminous efficiency, good consistency and relatively low cost; and the probability of photoelectric parameter degradation as the amalgam is melted and flows into the lamps is small.